Fusible link



Jan. 14, 1947. w, ROESSNER i. 2,414,243

FUS IBLE LINK Filed Sept. 28, 1945 13m@ will Patented Jan. 14, 1947 UNITED STATES PATENT OFFICE FUSIBLE LINK William L. Roessner, DenverC,olo,. Application September 28, 1945, SerialNo. 619,219

This invention relates to fusible links for controlling safety devices such as window and door closing means, rire extinguishers and the like intended to prevent the spread of fire.

In some uses of the device, the fusible link constitutes part of a, chain or other restraining or suspending means whereby pull is exerted on the link in opposite directions. In other uses of the device, the fusible link cooperates with means whereby pressure is exerted against the link from opposite directions. These links are known, respectively,` as the pull and l"push types. Certain-forms of links herein shown and described may be used either as the pull or the push type.

The fusible links of my invention comprise two identical elements connected together in superposed relation by means of fusible metal having relatively low melting points. In the prior art may be found a simple embodiment of fusible link consisting' o1" two iiat pieces of metal, rectangular in shape, superposed in partially overlapped relation, the non-overlapped portion of each piece being provided with an aperture for receiving a hook or the like, and the overlapped portions being connected together by fusible solder. When the fusible solder melts under inuence. `of heat and pull is being exerted on the elements, said elements separate by movement in opposite directions longitudinally of the link and parallel to the direction of stress. Although the releasing action of these fusible links is relatively satisfactory, depending on the low melting point of the alloy used to connect the elements, such links have been found to be inefficient in holding power and incapable of withstanding the required stresses. Consequently the elements separate and release prematurely, and fail to. restrain the de vices they are intended to. control.

The main object of the invention isl tov provide fusible links of the push and pull types which are constructed so as to be capable of sustaining their intended burden withoutV unintended or premature release or separation of the elements constituting the links, notwithstanding the use as the element-connecting means of alloys of low melting points not inherently capable of with standing the tensile stresses imposed upon them when embodied in said fusible links.

Another object is to provide fusible links ex-` ceedingly small in size and area, but having the capacity to resist relatively greattensile strain and to sustain relatively great pressure without premature or unintended separation of the ele@A ments.

Another object is to provide a. construction capable oi instantaneous release of the elements 11 Claims. (Cl. 16S-.42)

when the alloy connecting the elements-is sub1. y

jected to heat.

combination with a stress bearingelement.

This result is accomplished by4 emp'oying; a quick heat .transmitting elementin- Other objects and advantages will appear from the following description.

In the drawing:

Fig. l is a pla-n view of my pull type fusible link which may also be used as a push type link,

and Fig. 2 is a plan view of one of the two identical elements comprising said link.

Fig. 3 is a plan View of a push type fusible link which may also` be used as a pull type link, and Fig.34 is a plan view of one of the two identical elements comprising said link.

Figs 5, 7 and 9 are plan views, respectively, of modified forms of push type fusible links, and Figs. 6, 8- and 10 are plan views, respectively, of one of the two identical elements comprising the links shown in Figs. 5, 7 and 9.

Fig. l1 is an elevational edge view of the link shown in Fig. l, and Fig. 12 is an elevational edge view of the link shown in Fig. 5.

Referring to thatA embodiment of the invention shown in Figs. 1 and 2, the fusible link there shown as. a pull type link comprises identical elements' llt and Il in the form of flat pieces of metal, such as brass or other suitable material, each having onestraight longitudinal edge, and superposed in such manner that the straight edges are located at Aopposite sides of the assembled device. The pointed portions l2, I3, M of the element HI are at one longitudinal side and the pointed portions l5, I6, I1 of the member H are directed toward the other longitudinal side of the link. When thus superposed and connected,` the elements I@ and Il form two openings !8, I9., through which extend S-hooks or other stress exerting means 2li, 2l, respectively. In these rlgures, the means 2li, 2l are Vshown in section. They maybe of Various forms and are designed to be connected to the safety devices intended t0` be controlled. The overlapped portions of the elements Ill, Il are connected together by lowV melting point solder, indicated at 4t in Fig. 11.

When heat melts the solder, the elements lil, il separate by movement laterally in opposite directions substantially at right angles to the directions of stress.A This lateral movement of the elements lll, H is due to the action of the stress exerting means 29, 2| sliding along and bearing on the edges 22 of the element Hl and the edges 23, oi the element Il, as said means 2Q, 2| pull in opposite directions awayv from each other. The edges. 22, 22 and 23, 23v are diagonally disposed relatively to the direction of stress imposed on the linkg. The edges 22 of the element I are divergent with respect to each other, as are also the edges 2 3, of the element Il with respect to each other. l

The fusible link shown` in Fig. 3 comprises two identical elements 24.. 25,-0ne of which is shown. detahed nFi-g. 4.. The elements are superposed to a lesser degree, As indicated by the positions of the stress exerting means 20, 2|, bearing against the divergent edges 28, 29 of the respective elements 24, 25, lthe link as shown is a push type link in which the overlapped portions 26,

2l bear a, minimum of the holding burden, but

this link could be employed as a pull type of link if desired. When the solder melts, the elements 24, move in opposite side-wise movements due to the bearing pressure of the means 29, 2| as they slide on the edges 28, 29. i

The push type link shown in Fig. 5 is relatively small in size and area and is well adapted to be embodied in devices providing limited space. The link comprises elements in at plate form, indicated at 33, 3|, arranged in superposed relation and held together by low melting point solder, indicated at 41 in Fig. 12. The pressure exerting means 29, 2l bear against the divergent edges 32, 33 of the respective elements 30, 3l. When the solder melts said elements separate and move sidewise due to the pressure exerted by said means 2i), 2| against the edges 32, 33. The link shown in Fig. 5 cannot be employed as a pull type link as can the links of Figs. 1 and 3.

The push type link of Fig. '7 comprises two identical elements such as shown at 34, 35, one of which is shown detached in Fig. 8. Said elements have diagonal edges 36, 31, respectively, against which the stress exerting means 2U, 2| bear.

The elements 34, resemble those indicated at 3i heretofore described, and in addition are providedl with bent edges 38, 39, which in the assembled link turn upwardly and downwardly, respectively. The edge of one element serves as an abutment for the straight longitudinal edge of the other element and enhances the holding power of the fusible connecting means between the elements without interfering with the separation of said elements when the fusible means becomes melted.

Fig. 9 shows another form of push-type link comprising identical elements 40, 4I, having diagonal edges 42, 43, respectively, and end members 44, which provide additional overlapping area for solder connection. The members 20, 2l, exerting pressure against the diagonal edges 42, 43, cause the elements 40, 4l to move apart by sidewise or lateral movement when the solder` melts under influence of heat. While the end members 44, 45 increase the holding power of the element connecting material, they do not interfere'with the separation of the elements when the said material is subjected to heat.

The two elements which comprise each of the aforesaid forms of fusible links may be of equal' thicknesses, as shown in the edge View, Fig. 11, or they may be of different thicknesses as shown in the edge view of Fig. 12. The elements composing the link must be of sufficient thickness to provide required strength to prevent buckling in the push type 'and breaking in the pull type of link. By making one of the elements-extremely thin, its heat transmitting capacityis increased and speeded, and the other element can be made of sufficient thickness to sustain the stresses imposed upon the link as a whole. 'Ihus extremely quick releases are obtained under influence of heat without premature -or unintended vsepara'- 4 tion of the elements. This feature of construction, shown in Fig. 12, may be embodied in the several forms of links disclosed, either the push or pull type. In the drawing, the push type links of Figs. 5, '7 and 9 each comprise two sets of intersecting edges such as the edges 32-33, 36-31 and 42- 43, but it should be understood that the links could be straight edged at one end and have the intersecting edges only at the other end. In such case, the stress exerting means 20, for example, could function as heretofore explained by bearing against said intersecting edges, and the stress exerting means 2 I. would serve as restraining means for holding .the elements stationary until permitted to separate by the melting of the fusible material under influence of heat.

Prior art fusible links which comprise separable elements to which hooks or other pull exerting means are fastened, are objectionable because the said hooks or other stress exerting means are not released from the elements when they separate, and consequently the separated elements are carried with the stress exerting means and frequently interfere with the complete release and proper functioning of the safety devices controlled thereby and intended to be released.k In the devices of my invention, the stress exerting means 23, 2|, regardless of their nature or form, detachably and releasably engage the link elements, and when the latter separate as described herein, said means 20, 2l' are released also and their intended functions cannot be interfered with by any connection with the elements of the link.

In referring to the direction of stress imposedon the links, I refer to the direction parallel to or aligned with the longitudinal dimension of the link, such stress being imposed byV the means 20 and 2l pulling away from each other as in the pull type or pressing toward each other as in the push type of link. My experiments have shown that prior art links in which the elements separate by moving in the direction of stress do not have the holding power which I have attained in my link wherein the elements separate by moving laterally of the direction of stress. Consequently, I have been able to employ alloys of very low melting point, such as F., without premature release of the elements while being subjected to substantial stress. Prior art devices employing 153 F. fusibleV material have less holding power than the links of my invention employing substantially lower melting point alloys such as the 130 F. fusible material referred to. It is believe-d that this increase in holding power is due to the distribution of stress in the link in lateral directions relatively to the direction of imposition of the stress, and consequent relieving of the link from the straight 1ongitudinal pull or push imposed by the means 20 and 2l. To be able to use low melting point fusible material for connecting the elements while at the same time maintaining the required holding power to withstand substantial stresses is a feature of great value in obtaining quick release of safety devices4 controlled by'the link without prematu'reor unintended ,release of the elements. Changes may be made in the form and de- "tails of construction of the elements of my deviceA without departing from the scope of the invention as set forth in the appended claims.

I claim: 1. A fusible link comprising two separable ele-' ments, a layer .of fusible material between said` elements connecting them together in superposed relation, each element having two edges extending at angles other than right angles to the direction of stress imposed on the link, each of said edges of one element intersecting one of said edges of the other element, and means detachably engaging said edges at their intersecting points and exerting stress on said link in opposite directions whereby said engaging means slide along and bear against said edges and said elements are caused to move bodily'laterally of the direction of stress when said fusible material melts under influence of heat.

2. A fusible link comprising two separable elements, one of said elements being a quick heat transmitting element of less thickness than the other, a layer of fusible material between said elements connecting them together in superposed relation, each element having two edges extending at angles other than right angles to the direction of stress imposed on the link, each of said edges of one element intersecting one of said edges of the other element, and means detachably engaging said edges at their intersecting points and exerting stress on said link in opposite directions whereby said engaging means slide along and bear against said edges and said elements are caused to move bodily laterally of the direction of stress when said fusible materia?. melts under influence of heat.

3. The fusible link defined by claim 1, in which each of sai-d elements is provided along one longitudinal edge with a bent portion which serves as an abutment for the opposite edge of the other element.

4. A fusible link comprising two separable elements, a layer of fusible material between said elements connecting them together in suoerposed relation, and means detachably engaging said elements and exerting stress on said link in opposite directions, said elements when connected presenting divergent bearing surfaces to said stress exerting means whereby said elements are caused to move bodily laterally of the direction of stress imposed on said link, when said fusible f material melts under influence of heat, said stress exerting means becoming disengaged from said elements when said elements have moved from superposed relation.

5. A fusible link comprising two separable elements, one of said elements being a quick heat transmitting element of less thickness than the other, a layer of fusible material between said elements connecting them together in superposed relation, and means detachably engagingsaid elements and exerting stress on said link in opposite directions, said elements when connected presenting divergent bearing surfaces to said stress exerting means whereby said elements are caused to move bodily laterally of the direction of stress imposed on said link, when said fusible material melts under influence of heat, said stress exerting means becoming disengaged from said elements when sai-d elements have moved from superposed relation.

6. The fusible link dened by claim 4, in which each of said elements is provided along one longitudinal edge with a bent portion which serves as an abutment for the opposite edge of the other element.

7. A fusible link of the push or pull type comprising two separable elements, a layer of stress when said fusible fusible material between said elements connecting them together in superposed relation, each element having at one of its sides two pairs of converging edges, each of said edges of one element intersecting one of said edges of the other element and forming a pair of openings in the link, and means in said openings detachably engaging said edges at their intersecting points and exerting stress on said link in opposite directions, whereby said engaging means slide along and bear against said edges and said elements are caused to move laterally of the direction of stress when said fusible material melts under inuence of heat.

8. A fusible link of the push or pull type comprising two separable elements, one of said elements being a quick heat transmitting element o1- less thickness than the other, a layer of fusible material between said elements connecting them together in superposed relation, each element having at one of its sides two pairs o1" converging edges, each of said edges of one element intersecting one of said edges of the other element and forming a pair of openings in the link, and means in said openings detachably engaging said edges at their intersecting points and exerting stress on said link in opposite directions, whereby said engaging means slide along and bear against said edges and said elements are caused to move laterally of the direction of stress when said fusible material melts under influence of heat.

9. A fusible link of the push type comprising two separable elements, a layer of fusible material between said elements connecting them together in superposed relation, each element having an edge extending at an angle other than a lright angle to the direction of stress imposed on the link, said edge of one element intersecting said edge of the other element, restraining means releasably bearing on one end of the link, and means releasably engaging said edges at their intersecting point and exerting stress on said link whereby said engaging means slide along and bear against said edges and said elements are caused to move laterally of the direction of stress when said fusible material melts under influence of heat.

10. A fusible link of the push type comprising two separable elements, one of said elements being a quick heat transmitting element of less thickness than the other, a layer of fusible material between said elements connecting them together iny superposed relation, each element having an edge extending at an angle other than a right angle to the direction of stress imposed on the link, said edge of one element intersecting said edge of the other element, restraining means releasably bearing on one end of the link, and means releasably engaging said edges at their intersecting point and exerting stress on said link whereby said engaging means slide along and bear against said edges and said elements are caused to move laterally of the direction of material melts under influence of heat.

11. The fusible link defined by claim 10, in which each of said elements is provided along one longitudinal edge with a bent portion which serves as an abutment for the opposite edge of the other element.

WILLIAM L. ROESSNER. 

